Copolycondensation products of beta-haloalkyl phosphates and dialkyl phosphonates

ABSTRACT

Copolycondensation products of β-haloalkyl phosphates and dialkyl phosphonates are useful fire retardant agents. The products are prepared by heating the starting materials at a temperature of about 110° to 250° C., preferably in the presence of a nucleophilic catalyst, until at least one mole of alkyl halide per mole of phosphonate is driven off. Preferred are copolycondensation products obtained by substantially complete removal of halogen as alkyl halide.

This is a division of application Ser. No. 858,316 filed Dec. 7, 1977,now U.S. Pat. No. 4,152,371; which is a division of Ser. No. 811,972,filed July 5, 1977, now U.S. Pat. No. 4,086,303; which is acontinuation-in-part of U.S. Ser. No. 783,995, filed Apr. 4, 1977, nowabandoned, which, in turn, is a continuation-in-part of U.S. Ser. No.558,862, filed Mar. 17, 1975, now abandoned which, in turn, is acontinuation-in-part of U.S. Ser. No. 410,583, filed Nov. 12, 1973, nowabandoned.

This invention relates to condensation products of β-haloalkylphosphates and dialkyl phosphonates and to their use as fire retardantsfor urethane foams, polyesters and other flammable polymers andtextiles. More particularly, it relates to copolycondensation productsof β-haloalkyl phosphates having from 2 to 4 carbon atoms in the alkylmoiety and dialkyl phosphonates, said products being obtained by heatingthe starting materials in the presence of a nucleophilic catalyst.

β-haloalkyl phosphates, particularly tris(2-haloethyl)phosphates such astris(2-chloroethyl)phosphate, are known compounds and have been used asfire retardant agents in various flammable polymers such as polyurethanefoams. The fire retardant properties of tris(2-haloethyl)phosphates havebeen significantly improved by the recent development of a condensationprocess to obtain liquid poly(haloethyl-ethyleneoxy)phosphates. Thesephosphates and the method for their preparation are more fully describedin U.S. Pat. No. 3,896,187, which issued on July 22, 1975. The reactioninvolves a homopolycondensation, in the presence of a basic catalyst,with loss of ethylene dichloride and formation of oligomeric phosphates.This homopolycondensation reaction, however, has certain limitations.For example, it is virtually impossible by this reaction to prepareliquid products having more than above 15% phosphorus.

It is an object of this invention to prepare phosphorous-containingflame retardant agents having a phosphorus content greater than 15%.Additionally, the homopolycondensation reaction cannot be driven tocompletion, i.e., removal of all of the halogen, without gelation of theproduct. Thus, where excellent non-corrosive and/or extremely goodelectrical properties are desired, one cannot obtain the necessarynon-halogen containing product. Furthermore, since all of the halogencannot be removed, the product can continue to give off volatilehalogenated fragments during fabrication or during use in a plastic.Such volatile fragments represent undesirable air pollutants. It is afurther object of the present invention to obtain, in a preferredembodiment, a non-halogen containing and non-gelling condensationproduct.

By the prior art homopolycondensation of tris(2-haloethyl)phosphates, ithas not been possible to prepare water soluble phosphorus-richnon-volatile flame retardant products suitable for aqueous textilefinishing processes. It is therefore another object of this invention tomake available such water-soluble phosphorus-rich non-volatile products.

It has now been found that copolycondensation of a β-haloalkyl phosphateand a dialkyl phosphonate yields a condensation product which can be oflow halogen content or even free of halogen, is resistant to gelation,and is higher in phosphorus content than homopolycondensed β-haloalkylphosphates. Furthermore, these products are highly effective fireretardant additives for urethane foams, polyesters and other flammablepolymers and textiles. These copolycondensation products are obtained byheating the starting materials together until at least about one molarequivalent of alkyl halide is released, generally at a temperaturewithin the range of about 110° to 250° C., preferably 120° to 230° C.,and preferably in the presence of a nucleophilic catalyst. In mostinstances, the products obtained are clear liquids of little or no colorand odor and are thus suitable for a variety of fire retardant uses.

The β-haloalkyl phosphates usable in the practice of this inventioncontain at least one haloalkyl group of from 2 to 4 carbon atoms,preferably a 2-haloethyl group. Preferred, because of their reactivity,are the tris-haloalkyl phosphates particularly thetris(2-haloethyl)phosphates in which the halogen is chlorine or bromine.Most preferred is tris(2-chloroethyl)phosphate, althoughtris(β-chloroisopropyl)phosphate, tris(β,β'-dichloroisopropyl) phosphateand tris (2,3-dibromo-n-propyl)phosphate are also quite satisfactory foruse. Also usable are the polycondensed 2-haloalkyl phosphates ofabandoned application Ser. No. 164,928, filed July 21, 1971, tetrakis(2-haloalkyl) alkylene diphosphates, hexakis (2-haloalkyl) trimethylolalkane triphosphates and the like.

Where a mono(β-haloalkyl) phosphate or a bis(β-haloalkyl) phosphateether is used, the remaining ester groups can be any organic radicalswhich do not interfere with the polycondensation reaction. For example,these can be alkyl groups of from 1 to 20 carbon atoms, particularlyalkyl groups of from 1 to 4 carbon atoms; aryls, e.g., phenyl; alkylsubstituted by non-interfering radicals, e.g., alkoxyalkyls such asmethoxyethyl, hydroxyalkyls such as hydroxypropyl; cyanoalkyls;aralkyls, such as benzyl or α-methylbenzyl; substituted aryls, such astolyl, xylenyl, isopropylphenyl, t-butylphenyl, or chlorophenyl; and thelike. These are given as illustrative only, and are in no way intendedto be inclusive of all such compounds.

The dialkyl phosphate starting material is a compound of the formula:##STR1## In this structural formula, R' represents alkyl of from 1 to 20carbon atoms, alkenyl of from 3 to 20 carbon atoms, or aryl of from 6 to20 carbon atoms which may be mono- or poly-substituted with, e.g., alkylof from 1 to 4 carbon atoms or halogen. R represents alkyl of from 1 to4 carbon atoms. Preferably, R' represents alkyl of from 1 to 4 carbonatoms or phenyl. Preferred as R is methyl. Most preferably, the dialkylphosphonate is dimethyl methylphosphonate. Mixtures of dialkylphosphonates may also be used.

The copolycondensation reaction can be run without a catalyst, but, topermit lower temperatures and/or shorter reaction times, it ispreferably conducted in the presence of a nucleophilic catalyst.Suitable nucleophilic catalysts include alkali metal and alkaline earthcompounds conventionally recognized as bases, for example, oxides suchas sodium oxide, potassium oxide, magnesium oxide, calcium oxide, andthe like; alkali metal and alkaline earth hydroxides, such as sodiumhydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide,and the like; the corresponding carbonates and bicarbonates, such assodium carbonate and bicarbonate, potassium carbonate and bicarbonate,magnesium carbonate and bicarbonate, calcium carbonate and bicarbonate,and the like; alkoxides, such as sodium methoxide, potassium ethoxide,magnesium ethoxide, calcium ethoxide, and the like; phenolates, such assodium phenolate, potassium phenolate, calcium phenolate, and the like;salts of strong bases and weak volatile acids such as alkali metal andalkaline earth metal acetates, phosphates, chlorides, and bromides; andsalts of organic phosphorus acids and partial phosphate esters. Organicbases such as amines, for example, pyridine, quinoline, triethylamine,tetramethyl quanidine, N-methylmorpholine, butylamine, aniline, and thelike may be used. Additionally, very weak organic bases such as amides,for example N-methylpyrrolidone and hexamethylphosphoric amide, areeffective.

The definition of nucleophilic catalyst in the context of the presentinvention extends to those substances known as "Lewis bases," i.e.,electron pair donors, and thus includes, for example,trialkylphosphines, triphenyl phosphines, tributyltin oxide, and thelike. Where, for example, the phosphate is a tris(2-haloethyl) phosphateand a catalyst is employed, the true catalyst is believed to be theanion of a salt of bis(2-haloethyl) phosphate prepared in situ by thecleavage of tris(2-haloethyl) phosphate with a salt whose anion issufficiently nucleophilic to effect the cleavage. Thus, substances notnormally considered bases such as alkali metal halides, e.g., sodiumchloride, sodium bromide, and the like, potassium chloride, potassiumbromide, and the like, are also included within the term "nucleophiliccatalyst" as used herein inasmuch as they are sufficiently nucleophilicto effect the desired cleavage. Suitable quantities of catalyst are froma few parts per million, e.g., 50 p.p.m., up to about 10% by weight,preferably 0.01-5% based on the weight of the reaction mixture.

The reaction mixture, with proper amount of catalyst, if desired, and inproper molar ratio of starting materials, is heated to a temperaturewithin the range of from about 110° to about 250° C., preferably120°-230° C. An alkyl group of the dialkyl.phosphonate combines with ahalogen atom of the β-haloalkyl phosphate, splitting off an alkylhalide. At the same time, an alkylene linkage is formed between thephosphonate and the phosphate. Thus, in theory, the first reactionscheme is, using a β-haloethyl phosphate as an illustration, ##STR2## inwhich X is halogen, R and R' are as defined above, and R" and R"' arethe other ester groups on the β-haloalkyl phosphate.

The foregoing scheme represents the reaction which would occur ifneither R" nor R"' was a β-haloalkyl group; a product containing twophosphorus atoms is formed, and no further condensation would occur evenif there were an excess of unreacted dialkyl phosphonate and reactionconditions were maintained.

If, on the other hand, there are additional β-haloalkyl groups in thephosphate--i.e., if the phosphate were a bis(β-haloalkyl) phosphate or atris(β-haloalkyl) phosphate--additional condensation could occur if thereaction conditions were maintained. Illustrative of thesepolycondensation reactions are those shown below. It should be notedthat these reaction schemes represent "idealized" situations. Wherethere is more than one reaction group in the phosphate compound, i.e.,in bis(β-haloalkyl) and tris(β-haloalkyl) phosphates, somepolycondensation may occur with a portion of the phosphate while anotherportion thereof may remain unreacted or may form a "lower" condensationproduct than would be expected from stoichiometrical formulae. Thus,even where only one condensation product formula is hereinafterindicated, it must be realized that this formula represents a majorcomponent of the condensation product and that amounts of higher andlower condensation products are generally coproduced, and therefore theproducts of the process are generally mixtures.

Reaction (A): tris(β-chloroethyl) phosphate and dimethyl methylphosphonate, 2 moles of phosphate per mole of phosphonate ##STR3## andrelated higher condensation products, and some ethylene dichloride.

Reaction (B): tris (β-chloroethyl) phosphate and dimethylmethyl-phosphonate, in equimolar amounts ##STR4##

Reaction (C): tris(β-chloroethyl)phosphate and dimethylmethylphosphonate, 2 moles of phosphonate per mole of phosphate ##STR5##

Reaction (D): tris(β-chloroethyl) phosphate and dimethyl methylphosphonate, 3 moles of phosphonate per mole of phosphate ##STR6## Theproduct is actually a mixture of this condensate and relatedphosphate-phosphonates of varying degrees of condensation.

Reaction (E): tris (β-chloroethyl phosphate and dimethyl methylphosphonate, the phosphonate being present in greater than 3 moles permole of phosphate ##STR7##

Reaction (F): tris(β-chloroisopropyl)phosphate and dimethyl methylphosphonate, 2 moles of phosphonate per mole of phosphate ##STR8##

Reaction (G): tris(β-chloroethyl)phosphate and diethyl ethylphosphonate,2 moles of phosphonate per mole of phosphate ##STR9##

Reaction (H): tris(2,3-dibromo-n-propyl) phosphate and dimethylmethylphosphonate, in equimolar amounts ##STR10##

Reaction (I): tris(β,β'-dichloroisopropyl) phosphate and dimethylmethylphosphonate, in equimolar amounts ##STR11##

Reaction (J): tris(β-chloroethyl) phosphate and dimethyl phenylphosphonate, 2 moles of phosphonate per moles of phosphate ##STR12##

Reaction (K): tris(β-chloroethyl)phosphate and dimethyl methylphosphonate, 2 moles of phosphonate per mole of phosphate, withadditionally 0.01 to 0.1 moles of dimethyl n-octadecyl phosphonate##STR13## but with ##STR14## end groups imparting a surfactant characterto the polycondensate.

Reaction L: tris(2-chloroethyl) phosphate and dimethyl allylphosphonate,2 moles of phosphonate per mole of phosphate ##STR15##

In the foregoing illustrations, the phosphate was usuallytris(β-chloroethyl)phosphate and the dialkyl phosphonate was usuallydimethyl methylphosphonate. These particular reactants, which arepreferred from the economic standpoint, were used here for illustrativepurposes only. It will be realized, of course, that analogous productscan be obtained by using any of the starting materials included withinthe ambit of this disclosure.

The condensate products obtained will, as illustrated by the foregoingReactions (A) through (E), depend largely upon the molar ratio of thephosphonate reactant to the phosphate reactant. Although products of thetype illustrated in all five of said reactions are within the scope ofthis invention, preferred are those made by processes wherein thehalogen originally present in the reactant mixture is substantiallyeliminated as alkyl halide (i.e. down to about 1% halogen or less). Inthe cases where the reactants are tris(2-haloalkyl)phosphates anddialkyl phosphonates, the preferred cocondensates are those resultingfrom at least 2 moles of phosphonate per mole of phosphate, in which thepolycondensation is carried to the point where essentially all of thehalogen (down to about 1% or less) has been driven off as alkyl halide.These preferred products, with the halogen removed, have the multipleadvantages of (1) higher percent phosphorus and greater flame retardantefficacy, frequently even more than expected on a phosphorus contentbasis; (2) resistance to further viscosity increase and gelation oncontinued heating; (3) less smoke and toxic fumes in processing orcombustion of polymers containing these flame retardants. Thesubstantial elimination of halogen as alkyl halide can be accomplishedby using ratios of dialkylphosphonate to tris(β-haloalkyl)phosphate ofabout 2:1 or higher.

In this especially preferred aspect of the invention, the reactionscheme is illustrated by Reactions (B-2), (C), (F), (G), (J), (K) and(L). The symbol x in the product formulae represents the degree ofpolymerization, which is at least 2 and which would approach infinity asa limit if the reactants were in perfect 2:1 molar ratio and there wereno side reactions which produce end groups. In fact, with a molar ratioof 2:1, one obtains products of very high viscosity, up to, for example40,000 centipoise (25° C.).

In general, the polycondensation reaction scheme for a tris(β-haloalkyl)phosphate and a dialkyl phosphonate, in molar ratio of about 2 moles ofphosphonate per mole of phosphate is ##STR16## in which R, R' and X areas defined above and Q is alkylene of from 2 to 4 carbon atoms.

Also within the preferred aspect of this invention is the reaction wherethe molar ratio may be 3 moles of phosphonate per mole of phosphate, andthe idealized reaction scheme is: ##STR17## As explained above, however,some higher condensation products will also be formed. This aspect ofthe invention is illustrated by reactions (D) and (E) above.

Where even higher then a 3:1 ratio of phosphonate to phosphate is used,the formation of higher condensed products (involving displacement oftwo R groups from some of the phosphonate) will be repressed and theactual results will approach more closely the idealized equation, withexcess phosphonate remaining unreacted. The excess phosphonate can beleft in or distilled out depending on purity requirements of theproduct.

A molar ratio of phosphonate to phosphate substantially lower than 2:1,as in reactions (A) and (B-1), represents a nonpreferred aspect of thisinvention. The products represented by Reaction (A), for example, wherethe phosphonate to phosphate molar ratio is 1/2:1, are useful flameretardants having much lower volatility than their parent compounds.They are, however, relative to the preferred compounds of thisinvention, somewhat inferior since, on further heating, they undergogelation and/or emission of volatile halides.

In the practice of the process for producing the polycondensate productsof this invention, the reaction is allowed to proceed until thetheoretically produced amount of alkyl halide (e.g., methyl chloride)by-product is obtained. When the polycondensation reaction has beencompleted, the crude residual product is suitable for use in certainnon-critical applications such as thermosetting resin systems (i.e.,phenolics or aminoplasts) where volatile and/or acidic components can betolerated. Since these resins themselves will give off volatilecomponents during curing, and since in such systems acidic componentscan be tolerated or may even be helpful as cure promotors, the presenceof alkyl halide and acidic by-products is often found not to bedetrimental.

For applications where volatile components are generally undesired, suchas for flame retardant additives used in polyester resins, the residualproduct can easily be freed of volatiles (e.g., alkyl chloride, alkylenedichloride, and any unreacted starting materials by purging with aninert gas and/or by application of vacuum, with or without heating.

In addition to volatile components, which can easily be removed asindicated, the residual polycondensation products also are generallyfound to contain by-product acidic structures to some extent. Where thepolycondensation products are relatively small molecular weight productssuch as the sort illustrated by the formulae:

    (ClCH.sub.2 CH.sub.2 O).sub.2 P(O)OCH.sub.2 CH.sub.2 OP(O)(CH.sub.3)(OCH.sub.3)

or

    [(ClCH.sub.2 CH.sub.2 O).sub.2 P(O)OCH.sub.2 CH.sub.2 O].sub.2 P(O)CH.sub.3,

the product may be freed of acidic by-products by such simple means aswashing with an aqueous solution of a base, such as sodium carbonate.However, where the product is a relatively higher molecular weightpolymer such as ##STR18## the acidic by-product structures represent endgroups on many or most of the polymer chains and removal by simplewashing means becomes impracticable.

It is a feature of the present invention that means has been found forsubstantially neutralizing such acidic by-products thus rendering themharmless when the polycondensation product is to be used forapplications where acid can cause catalysis problems such as in urethanefoams or textile finishes. It is a further significant feature of theinvention that in the neutralization of said acidic by-products, meanshas been found for conveniently creating useful functional groups, inparticular alcohol end groups. Where said acidic structures occur as endgroups on most or all of the polymer chains, the introduction of alcoholend groups makes the polycondensation polymer a "reactive" flameretardant rather than an "additive" flame retardant, i.e., the flameretardant can become attached by the alcohol end group to a polymermatrix such as that of a urethane foam, polyester, aminoplast resin,phenolic resin or the like thus imparting flame retardant propertieswhich are not readily subject to loss resulting from migration,volatility or leaching.

The acidic structures present in the polycondensation products of theinvention appear to be of two principal types: (1) true acids and (2)structures which generate acid rapidly in water. Experimental data showthat the acid content as determined by titration of the product inwater, after a few minutes waiting time, is substantially in excess ofthe acid content as determined by titration of the product in alcoholsolution. It is believed that the difference between these two acidcontent values is represented by labile cyclic glycol phosphate esterrings illustrated by the structure ##STR19## In water these groups openwithin minutes at room temperature to form true acid groups, exemplifiedby the formula ##STR20## In alcohols, especially in primary alcohols,these cyclic ester groups open to neutral ester groups, exemplified bythe formula ##STR21## The other acidic structures present in thepolycondensation product are believed to be true acidic groups of thetype <P(O)OH, and undergo titration with base identically in alcohol orwater. Some pyrophosphate structures may also be present in minoramounts.

Several alternatives exist for elimination of these acidic structuresfrom the polycondensation products of the invention. Direct introductionof an alkylene oxide such as ethylene oxide, propylene oxide, butyleneoxide, octylene oxide, epichlorohydrin, glycidol, epibromohydrin,styrene oxide, glycidyl ethers such as the diglycidyl ether ofbisphenol-A, epoxy cycloalkanes such as epoxycyclohexylmethylepoxycyclohexylcarboxylate, butadiene diepoxide, vinylcyclohexenediepoxide, 4,4,4-trichloro-1,2-epoxy-butane, or the like will rapidlyneutralize the true acid groups, yielding 2-hydroxyalkyl structures intheir place, and will slowly neutralize the labile cyclic ester groupsby a reaction which stoichiometrically amounts to ring opening of boththe cyclic ester and epoxide ring, forming a linear ester structure intheir place. Such direct epoxide reactions with the crude acidicpolycondensation products of the invention are useful but tend to berelatively slow and difficult to carry absolutely to completion. Anorthoester such as trimethyl orthoformate will neutralize the true acidstructures by conversion to ester, but will not eliminate the cyclicesters.

The preferred process for eliminating the acidic structures is a processwherein (1) the labile cyclic ester structures are opened by reaction atambient temperatures of about 20° to about 180°, preferably 50° to 150°,with a reagent

    YOH

where Y is alkyl of from 1 to 20 carbon atoms unsubstituted orsubstituted by noninterfering substituents, and (2) the true acidstructures are neutralized by reaction with an epoxide or an orthoesterto form ester groups. These two steps can be run concurrently orsuccessively.

As the group Y in the ring-opening reagent, any alkyl or substitutedalkyl group may be used so long as the substituent or substituents donot adversely affect the ring-opening reactions and do not causeundesirable side reactions, e.g. reactions with portions of thepolycondensation product which would result in a loss of or reduction infire-retardant properties. Usable substituents this include aryloxy,halogen, alkoxy, aryl, acyl, acyloxy, hydroxy, amido, alkylthio,arylthio, carbalkoxy, carboxamido, cyano and nitro. Suitablering-opening reagents are exemplified by methanol, ethanol, n-butylalcohol, lauryl alcohol, other monohydric alkanols having from 3 to 12carbon atoms, allyl alcohol, 2,3-dibromopropanol, tribromoneopentylalcohol, dibromoneopentylene glycol, ethylene glycol, dibromobutenediol,diethylene glycol, methoxyethanol, ethoxyethanol, butoxyethanol,2-chloroethanol, benzyl alcohol, glycerol, pentaerythritol,dipentaerythritol, trimethylolethane, trimethylolpropane, sorbitol,glucose, sucrose, lactose, methylglucoside and polyoxyalkylated(especially polyoxyethylated or polyoxy propylated) derivatives of anyof the aforementioned polyols, acryloxyethanol, acetoxyethanol,methacryloxyethanol, N-hydroxymethylacrylamide, vinyl hydroxyethylether, methylolmelamines, methylolureas, and hydroxymethylphenols.

In addition to the above-described ring-opening reagents water may alsobe used to open the glycol phosphate ester ring. In this case, thepolycondensation product would not be neutralized by the ring-openingreaction and, if neutralization is desired, it will be necessary toreact the product with an expoxide or an orthoester group.

This ring opening step allows the introduction of valuable functionalgroups. Where the polycondensation product is of large molecular size,most of the molecules will be terminated by the aforementioned labilecyclic phosphate ester groups and therefore at least one functionalgroup can be imparted in the ring-opening step to most of the molecules.Through the choice of water, a monohydric alcohol, a diol or a polyol asthe ring opening reactant, options are made available as to the averagefunctionality of the product. In the following equations thephosphonate-phosphate chain, such as ##STR22## is represented by thesymbol Z and the chemistry of the cyclic end group is illustrated by thefollowing reaction schemes: ##STR23## The other end group on Z can bethe same as the end group shown, or can be, for example (CH₃O)(CH₃)P(O)-- or (HOCH₂ CH₂ O)(CH₃)P(O)--, the latter resulting from(HO)(CH₃)P(O)-- plus ethylene oxide. In general, only the averagefunctionality of the products is known, the products being mixtures asheretofore explained.

Neutralization of the true acid structures is accomplish by treatmentwith an epoxide reagent or an aliphatic orthoester. The epoxide reagentis a compound having one or more ##STR24## groups. These include thealkylene oxides set forth above. Suitable orthoesters are compoundshaving a

    --C(OR).sub.3

group in which R is hydrocarbyl, preferably alkyl of from 1 to 6 carbonatoms. Particularly suitable is trimethyl orthoformate. Thisneutralization reaction may be run at a temperature of from about 25° toabout 225° C., preferably from 50° to 150° C., over a period rangingfrom 5 minutes to 24 hours.

By means of the Y group introduced in the ring-opening step as well asthe 2-hydroxyalkyl groups from the alkylene oxide, the products of theinvention can be made to have various controllable degrees of OHfunctionality, for example, OH numbers (as conventionally defined interms of mg. KOH/g) in the range of 30-100 for use in flexible urethanefoams or above about 100 for use in rigid urethane foams. The OH groupsalso serve as binding sites for incorporation of these products intodurable textile finishes, where a coreactant system such asdimethyloldihydroxyethylene urea plus an acid catalyst, amethylolmelamine, plus an acid catalyst, or N-methylolacrylamide plus afree radical conjointly with an acid catalyst may be employed. Whereunsaturated groups are present in the alcohol, as in several listedabove, these groups may act as binding site in polymerizable systemssuch as polyester resins or textile finishes cured by free-radicalmeans. Where a methylolmelamine, methylolurea or methylolphenol is usedas the reactant alcohol, these groups may act as binding sites inrelated thermosetting resins or resin finishes.

The following examples are here inserted to illustrate the practice ofthis invention. They are presented here for illustrative purposes onlyand are not to be construed as limitations.

EXAMPLE 1

This example illustrates the polycondensation reaction in which threemethyl methylphosphonate radicals replace three halogen atoms intris(2-chloroethyl) phosphate. A mixture of 285.5 g (1 mole)tris(2-chloroethyl) phosphate, 558 g (4.5 moles) dimethylmethylphosphonate and 1 g Na₂ CO₃ (catalyst) was heated at 158°-196° C.over 4 hours until 3 moles of methyl chloride (identified by boilingpoint) and a trace of ethylene dichloride were evolved. The reactionmixture was then stripped at a pot temperature of 159° C. at 0.5 mm toremove unreacted dimethyl methylphosphonate. The residual clear,colorless liquid, 432 g, was neutralized by adding 14 g of methanol andheating the mixture for 1 hour at 90°-100° C. (to open cyclic glycolphosphate rings) and then passing in ethylene oxide at 90°-110° C. untilthe acid number was reduced to less than 0.1 mg. KOH/g.

The resultant product was a colorless water-soluble liquid having 24.7%P, 0.1% Cl. Nmr and infrared spectra confirm that the structure isprincipally: ##STR25## plus small amounts of higher polycondensedoligomers and analogs containing hydroxyethyl groups.

EXAMPLE 2 Evaluation of Product of Example 1 as a Flame Retardant.

At 5 phr in a flexible urethane foam prepared as indicated in Example 5below, the resultant foam was self-extinguishing and non-burning (SENBR)both before and after the GM cycle, and gave greater than 90%transmittance by the standard fogging test. By contrast, the commercialfire retardant tris(dichloropropyl)phosphate required greater than 10phr to achieve the same inflammability rating, and failed the foggingtest.

In the GM cycle, (General Motors (Fisher Body) aging cycle), flexiblefoams are subjected to the following sequence of aging: 4 hours at -29°C., 16 hrs. at 38° C. (100° F.) and 100% relative humidity, 4 hours at-29° C., 16 hr. at 38° C. (100° F.) and 100% relative humidity, and 72hour at 93° C. (200° F.). This entire sequence is then repeated.

The standard fogging test measures fog tendency, which is a tendency ofplasticizers, flame retardants, etc., in automobile components--such asvinyl seat coverings and urethane foam cushioning--to cause a fog whichin turn causes glare and lack of transparency in the windows. Thistendency is measured by placing foam specimens in glass containers in anoven arranged such that the foams are warmed and the glass surfaces arecooled. The amount of loss of transparency is measured. Values above 90%are considered satisfactory; values below 90% are regarded as failures.

EXAMPLE 3

In order to evaluate the advantage of the essentially chlorine-freecopolycondensed product of Example 1 in respect to metal corrosion andvolatility, the product was heated on a tin-plated steel dish in an ovenat 135° C. for three hours. The product lost 8-9% by weight and did notcorrode the dish. The homo-polycondensed tris(2-chloroethyl)phosphate,on the other hand, lost 18% by weight and caused considerable corrosionto the dish.

EXAMPLE 4 Preparation and Characterization of 2:1 DimethylMethylphosphonate-Tris(2-Chloroethyl)Phosphate Co-Condensation Product

A mixture of 2480 g (20 moles) of dimethyl methylphosphonate, 2855 g (10moles) of tris(2-chloroethyl) phosphate and 20 g of sodium carbonate(catalyst) was stirred and heated in a vessel fitted with a refluxcondenser, allowing methyl chloride to escape from the outlet of thereflux condenser. Evolution of methyl chloride (identified by itsboiling point) ensued at about 140° C.; the temperature of the reactionmixture was raised over 41/2 hours to 183° C. and held about 1 houruntil the rate of methyl chloride evolution dwindled to a negligiblerate of 0.15 g per minute. At this point, the weight loss of theresidual reaction mixture was 1503 g, corresponding closely to thetheoretical 1515 g (30 moles) of methyl chloride for the theoreticalreaction indicated above.

That the reaction had resulted in the evolution of practically all ofthe chlorine content of the reactant as volatile methyl chloride wasalso confirmed by analysis of the residual reaction product for totalchlorine, which was found to be only 0.4%.

The product at this point had an acid content of 0.2 meg/g as determinedin methanol and a total acid plus cyclic ester content of 0.97 meg/g asdetermined in water, allowing 10 minutes hydrolysis time beforetitration; thus the cyclic ester content is estimated by difference tobe about 0.77 meg/g. The product at this point is suitable for flameretardant use in systems not sensitive to acid content, for example, inpolyester resins, but not generally suitable for use in urethane foamsbecause of the interaction of its acid component with the catalysts usedin urethane foam manufacture.

That very little free dimethyl methylphosphonate was present in theproduct was proved by vacuum stripping to 90° C. at 0.1 mm which causeda weight loss of only 4%.

EXAMPLE 5 Conversion of the Product of Example 4 to Neutral Alcohol

The product of Example 4 was admixed with 120 g (3.7 moles) of methanol,a small molar excess over the amount of cyclic ester indicated by thetitration assay described and heated at 95°-100° C. for 1 hour until themethanolic and aqueous titrations became 0.4 meg/g and 0.24 meg/grespectively, indicating only 0.16 meg/g of cyclic ester remaining. Theresidual acidity was then eliminated by introduction of ethylene oxideat 90°-97° C. over 5 hours.

The final product was a nearly colorless syrup, viscosity 6000 cps. at25° C., containing 23.3%P., 0.4% Cl, and having an OH number of 79.8.

When the methanol treatment is omitted and the crude product is treateddirectly with ethylene oxide to the point of neutrality, the OH numberis only 14.5 mg KOH/g. Such a low OH product is suitable as a flameretardant additive for urethane foams but has little bonding capabilityand can largely be removed by leaching the foam with a solvent.

EXAMPLE 6 Conversion of the Product of Example 4 to a Diol-terminatedAnalogue of the Product of Example 5

To 600 g of the product of Example 4 was admixed 10.6 g (0.59 mole) ofwater, substantially equivalent to the assayed amount of cyclic ester.After heating the mixture at 100° C. for 1 hour, the methanolic andaqueous titrations were found to be 1.04 meg/g and 1.06 meg/grespectively, indicating that essentially all of the cyclic ester hadbeen opened to 2-hydroxyethyl acid phosphate end groups of the structure##STR26## This acid product was neutralized by introduction of ethyleneoxide at 100° C. for 5 hours. The resultant product was found to have noacid content or cyclic ester content by methanol, KOH and aqueous NaOHtitrations. The OH number of this product was found to be 99 and the %Pwas found to be 22.0.

EXAMPLE 7 Use of Product of Example 5 in Flexible Urethane Foam as aPermanent Flame Retardant Reactant

A urethane foam formulation was made as follows:

    ______________________________________                                                             Parts by Weight                                          ______________________________________                                        Niax 16-46 polyol, a commercial                                                polypropylene glycol manu-                                                    factured by Union Carbide Corp.                                                                     100                                                    Water                  4                                                      Flame Retardant Product of                                                     Example 5             4                                                      Silicone L-548 surfactant, a                                                   commercial dimethylsiloxane                                                   polymer manufactured by Union                                                 Carbide Corp.         1                                                      Bis(dimethylaminoethyl) ether (catalyst)                                                             0.1                                                    N-Ethylmorpholine (catalyst)                                                  Stannous octoate (catalyst)                                                                          0.25                                                   Tolylene Diisocyanate Index                                                                          110                                                    ______________________________________                                    

A 1/8 lb./cu.ft. foam was obtained containing 0.67% P. This foam wasthen tested by the method of Federal Motor Vehicle Safety Standard 302and was found to have a rating of "Self-extinguishing-no burning rate"initially and after dry heat aging at 140° C. for 22 hours and"Self-extinguishing (2.8 inches per minute burn rate)" after 5 hourshumid autoclaving at 250° F. Tensile strength was 17.7 lb/sq. in.compared to 18.9 for the comparison foam without flame retardant. In thedry heat aging, a weight loss of only 1.2% was observed, while the foamwithout flame retardant lost 0.34% and a similar foam flame-retardantwith two commercial additive flame retardants (tris(dichloropropyl)phosphate and tetrakis(2-chloroethyl) dichloroneopentylene diphosphate)lost 7.3 and 2.5% respectively. That the product of Example 2 had becomebound to the polymer matrix was also shown by methylene chlorideextraction of the foam followed by phosphorus analysis, which showedthat 91% of the flame retardant was retained, contrasted to 0% and 16%retained in the case of the two additive flame retardants mentionedabove. The homo-polycondensed product of tris(2-chloroethyl) phosphatewas only retained to the extent of 31% in this test.

In the window-fogging test described in Example 2, the foam made usingthe product of Example 5 showed 93% retention of window-lighttransmittance whereas the two additive flame retardants allowed only 40and 87% transmittance respectively.

EXAMPLE 8 Use of Product of Example 5 in a Polyester Resin

The product of Example 5 was added at 5 phr to a chlorendic-acid-derivedpolyester resin (Hetron 24370, a product of Hooker Chemical Co.) and theresin cured as a 3-ply glass reinforced laminate (30% glass content) atroom temperature using methyl ethyl ketone peroxide and cobaltnaphthenate catalyst until a Barcol hardness of 53 was reached. Thecured product has an oxygen index of 35.8 and an HLT-15 flame retardanttest rating of 100. Substantially lower ratings were obtained using 5phr of trimethyl phosphate, triethyl phosphate, tris(2-chloroethyl)phosphate, polycondensed tris(2-chloroethyl) phosphate, or the 1:1copolycondensate of dimethyl methylphosphonate with tris(2-chloroethyl)phosphate (2 moles of CH₃ Cl removal per mole of phosphate).

The HLT-15 Flame Retardant Test is a test for flame retardancy ofreinforced laminates developed by Hooker Chemical Corp. It is designedto determine the self-extinguishing quality of resins in the form offiber glass mat reinforced laminates. In the rating systems, the toprating for flame retardancy is given the value of 100. A detailed methodof operations and further information concerning this test may be foundin a paper by A. J. Hammerl, "Burning Tests for Thermosetting Resins",given at the 17th Annual Technical and Management Conference onReinforced Plastics, in February, 1962.

Surprisingly, a 72 hour water boil of these polyester laminates removedonly 0.54% by weight, which compares favorably with the 3.6-3.8%extraction observed with poly(ethylene methylphosphonate) in ananalogous formulation. Since both flame retardants are, themselves,water-soluble, this resistance to leaching from the polyester resinobserved with the product of the present invention is surprising andunexpected.

EXAMPLE 9 Preparation of 2.14:1 Mole Ratio DimethylMethylphosphonate/Tris(2-chloroethyl) Phosphate CopolycondensationProduct

A vessel fitted with stirrer, thermometer, heating mantle, and verticalreflux condenser was charged with 5308 g (42.8 moles) of dimethylmethylphosphonate, 5710 g. (20 moles) of tris(2-chloroethyl)phosphate,and 40 g. of anhydrous sodium carbonate. After a brief nitrogen purge toremove air (and thus avoid possible oxidative color development thereaction mixture was raised to 135°, at which point methyl chloridebegan to be evolved from the condenser outlet. Over five hours thetemperature was gradually raised to 185° and held for 27 hours at whichtime measurement of the rate of methyl chloride evolution showed therate to have dwindled to 0.08 cc/min. At this point, weighing theremaining reaction mixture showed that a weight loss of 3044 g. hadoccurred, corresponding to 60.3 moles of methyl chloride (as against atheoretical loss of 60 moles). While stirring was continued, the reactorwas allowed to cool to about 92° under dry nitrogen. Then 282 g. (8.8moles) of methanol was added over 5 minutes. This quantity was a smallexcess over the calculated amount of cyclic glycol ester, 7.8 moles,which had been determined to be present by the fact that a sample heldfor 10 minutes in water and then titrated with 0.1-N NaOH to Bromphenolblue end point showed 1.14 millequivalents of acid plus cyclic ester pergram, whereas a titration of a sample in methanol with methanolic 0.1-NKOH to Bromphenol blue showed 0.16 milliequivalents of acid per gram;thus 0.98 milliequivalents of cyclic glycol ester per gram was presentby this assay method. The reaction mixture was heated for 2 hours at95°, at which point the two titration results were 0.27 meq. acid pluscyclic ester per gram and 0.17 meq. acid per gram; thus only 0.10meq.cyclic ester per gram remained by this assay method. At this point,a fast stream of ethylene oxide was introduced with stirring at 95°.After 4 hours, the titrations by both the aqueous and alcoholic methodwere nil. Heating was then stopped, ethylene oxide continued as thetemperature drifted down to 80°, then vigorous nitrogen sparging wasconducted at 90°-95° until dissolved volatiles were removed (found to bemostly dimethyl methylphosphonate). The weight change during thisdevolatilization step was 3.5%. To remove final traces of acid, whichreformed in the devolatilization step, the batch was briefly retreatedwith ethylene oxide at 95°. Alternatively, 1% of the non-volatilediepoxide of cyclohexenylmethyl cyclohexenylcarboxylate was added. Theproduct, by the ethylene oxide finishing method, had the followingcharacteristics:

Acid No.--less than 0.2 mg KOH/g.

OH No.--50±5 mg. KOH/g.

%P=22.8, 23.0

%Cl=0.45

Viscosity (25°); 6750 cps. (1/2 hr. sparge at 80° to remove ethyleneoxide raised this to 15,500 cps.)

Density: 1.381 (25°)

Refractive Index: 1.4634

Appearance: Clear light yellow syrup

Various alternative finishing steps, are described in subsequentexamples.

EXAMPLE 10 Cocondensation and Copolycondensation of DimethylMethylphosphonate With Tris(β',β'-dichloroisopropyl) Phosphate at 1:1mole Ratio

A mixture of 124 g. (1 mole) of dimethyl methylphosphonate and 431 g. (1mole) tris(β',β'-dichloroisopropyl) phosphate plus 1 g. Na₂ CO₃ catalystwas heated at 190° for 2 hours until 1 mole (50.5 g) of methyl chloridewas evolved. The residual mixture was then treated with ethylene oxideat 105° C. for 4 hours until nearly free of acidity. The elementalanalysis of the liquid product corresponded to CH₃ P(O)(OCH₃)--OC₃ H₅Cl--OP(O)(OC₃ H₅ Cl)₂. A reaction mixture of the same composition washeated for 8 hours at 184°-186° until 2 moles of methyl chloride wasevolved. The elemental analysis of the liquid product corresponded to[(--P(O)(CH₃)--OC₃ H₅ Cl--OP(O)(OC₃ H₅ Cl₂) (OC₃ H₅ Cl--)]_(x).Continued heating at 184°-190° led to darkening and finally to gelation.The products of the first two steps were syrups which, when compoundedinto a cellulose acetate film at 20% (by solvent casting), affordedself-extinguishing characteristics when the film was ignited from thebottom in a vertical configuration.

EXAMPLE 11 Copolycondensation of Dimethyl Methylphosphonate with Tris(2-chloroisopropyl) Phosphate at 2:1 Mole Ratio

A mixture of 248 g. (2 moles) of dimethyl methylphosphonate and 327.5 g(1 mole) of tris(2-chloroisopropyl) phosphate plus 1. g oftetraethylammonium chloride as catalyst was heated at 150°-185° until151 g (approximately 3 moles) of methyl chloride was evolved. Theresidual liquid is heated with 50 g. of methanol for 2 hrs. at 90° C.,then vacuum is applied to remove excess alcohol, then the product isheated with 50 g. of propylene oxide under reflux at 80° until thealcoholic KOH titration declined to less than 1 mg KOH/g. This steprequires a substantially shorter reaction time than is required if thealcohol treatment step is omitted. The reaction mixture was then spargedwith nitrogen under aspirator vacuum at 80° until it reached constantweight (less than 1 g. weight loss in 1 hr.). The product was a viscousliquid which functioned as a flame retardant when admixed with celluloseacetate (cast film) at 15%.

EXAMPLE 12 Dibromoneopentyl Glycol--Modified Copolycondensation Product

A mixture of 500 g of the crude copolycondensation product of dimethylmethylphosphonate and tris(2-chloroethyl) phosphate (2.14:1 mole ratio,as described in Example 9) and 131 g. dibromoneopentyl glycol wasstirred and heated at 98°-100° for 3 hours. At this time, titrations ofsamples of the reaction mixture to naphtholbenzein end point withalcoholic KOH showed 0.23 meq.acid/g., and titration with aqueous NaOHin water solution showed 0.28 meq. acid/g., indicating that the cyclicphosphate ester content of the crude condensation product had beensubstantially consumed by reaction with the dibromoneopentyl glycol. Theproduct mixture was then neutralized completely by the passage ofethylene oxide at 90°-100° for 4 hours. The resultant product was a paleyellowish syrup, completely water soluble, and having 18% P and 12.7% Brcontent, together with 1.6 millimoles of alcoholic functional groups pergram.

When this product (as an aqueous solution) was padded ontocotton-polyester fabric at 20% dry add-on along with 10% dry add-onN-methylolacrylamide and 1% ammonium persulfate catalyst, and cured at100°-140° C., the resultant product had excellent flame retardantproperties, durable to laundering. Such durable flame retardant finishesare similarly obtained with the products of examples 5, 6 and 9 oncotton, rayon and cotton-polyester fabrics.

EXAMPLE 13 Dibromopropyl--Modified Copolycondensation Product

In like manner to the preceding example, a product is made using 109 g.of 2,3-dibromopropanol in place of the dibromoneopentyl glycol. Theresultant product has 18.5% P, 13.1% Br, and 1.6 milliequivalent of OHend groups per gram. It similarly was water-soluble and afforded adurable flame retardant finish when co-cured with N-methylolacrylamideand a persulfate catalyst on cotton polyester fabric. It also affords adurable flame retardant finish on cotton or cotton polyester blends whenco-cured with a methylolmelamine or dimethyloldihydroxyethyleneurea andan acid catalyst such as ammonium chloride or zinc nitrate. Typical dryadd-ons are 10-25% of the phosphorus composition, 5-25% of theaminoplast. Typical curing conditions are 100°-190° C. for 0.1 to

EXAMPLE 14 Tribromoneopentyl-Modified Copolycondensation Product

In like manner to the Example 12,170 g. of tribromoneopentyl alcohol isreacted with the same crude 2.14:1 copolycondensation product. The endproduct, although not completely water-soluble, has sufficientemulsifying character to hold the insoluble components in suspensionwith only gentle agitation. In this form, the product is usable as aflame retardant finish for textiles. It contains 17.9% Br and 16.8% P.

EXAMPLE 15 Use of Ethanol and Various Epoxides in the NeutralizationSteps.

The crude copolycondensation product of 2.14 moles of dimethylmethylphosphonate and tris(2-chloroethyl)phosphate of Example 9 wasreacted with 10% by weight of ethanol by heating at 95° for 3 hoursuntil the aqueous NaOH and alcohol KOH titrations becamse almost equal.Two portions of the product were then treated with 3.5% by weight ofpropylene oxide and 4.5% by weight of epichlorohydrin, each at 95°,until the reaction mixture was substantially neutralized in each case.

EXAMPLE 16 Use of Diethylene Glycol in the Neutralization Step

The crude 2.14:1 dimethyl methylphosphonate/tris(2-chloroethyl)phosphate copolycondensation product of Example 9 was heated at 95° forone day with 10% by weight of diethylene glycol, until the alcoholic KOHtitration and the aqueous NaOH titrations of samples of the mixturebecame substantially equal. The product was then treated with ethyleneoxide at 90°-100°. The resultant clear colorless neutral water-solubleproduct had an OH number of 82 mg. KOH/g. and was a durable flameretardant when incorporated into a flexible urethane foam at 5 phr.

EXAMPLE 17 Use of Ethanol and a Diepoxide in the Neutralization Steps

A mixture of 500 g. of the crude 2.14:1 copolycondensation product ofExample 9, was reacted with 22 g. ethanol at 90°-100° for 2 hours. Atthis point, the alcoholic KOH titration showed 0.245 meq. acid per gram.Therefore, 0.245 millimole of a diepoxide ("ERL-4221", a product ofUnion Carbide Co., the diepoxide of cyclohexenylmethyl cyclohexenecarboxylate) was added per gram of crude product; i.e. 32 g. of thisdiepoxide was added. Heating was continued at 95° C. until the reactionmixture was acid-free. This procedure allows 0.245 millimole of epoxidegroup per gram to remain unreacted, as a stabilizing acid-acceptorcomponent to prevent development of acidity in storage and handling ofthe product. The product is usable as a flame retardant reactant inacid-sensitive urethane foam compositions. A similar objective isalternatively accomplished by addition of 0.1-5% of an epoxide, such asthe ERC-4221 diepoxide, to the already neutralized copolycondensationproducts, such as the finished products of Examples 12-16.

Further stabilization in storage and use of this product wasaccomplished by dissolving in it 0.1% of phenothiazine of anacetone-diphenylamine condensation product, both of which are knownantioxidants.

EXAMPLE 18 Preparation of Tris(2-chloroethyl)Phosphate/DimethylMethylphosphonate Copolycondensation Product Without Use of Catalyst

A mixture of 571 g. of tris(2-chloroethyl) phosphate and 531 g. ofdimethyl methylphosphonate was heated at 181°-197° C. until 287.5 ofmethylchloride was evolved; this required 26 hours. The product was thenheated at 95° with 28.2 g. of methenol, and finally treated withethylene oxide at 90°-100° until substantially neutral. The product wasuseful as a flame retardant at 5-10 phr. in a styrenated polyester.

EXAMPLE 19 Copolycondensation Product Modified by 2-HydroxyethylAcrylate and Glycidyl Methacrylate.

A mixture of 500 g. of the crude 2.14:1 mole ratio copolycondensationproduct of dimethyl methylphosphonate and tris(2-chloroethyl) phosphateof Example 9 plus 55 g. of 2-hydroxyethyl acrylate and 0.05 g. ofmethoxyphenol (as polymerization inhibitor) was heated at 90°-100° for41/2 hours. 23.4 g. of glycidyl methacrylate was then added and themixture was heated for 2 hours at 90°-100°. The resultant clear productcould be copolymerized in bulk with 10 parts per hundred of methylmethacrylate by heating at 80°-105° with a catalytic amount ofazobisisobutyronitrile (200 ppm) to afford a self-extinguishing casting.A similar product, affording a lower degree of cross-linking, wasobtained by using ethylene oxide in place of glycidyl methacrylate.

EXAMPLE 20 Copolycondensation Product Modified by 2-HydroxyethylCarbamate and the Methylolation Product Thereof

A mixture of 500 g. of the same crude copolycondensation product as inthe preceding example plus 52.5 g. of 2-hydroxyethyl carbamate washeated at 90°-95° for 12 hours, then ethylene oxide was passed in for 3hours at 90°-95°. The resultant product showed typical --NH₂ spectralbands at 1612-1618, 3200 and 3380 cm⁻¹. To this product was added 30 g.of paraformaldehyde and 10 cc. of triethylamine (as catalyst), and themixture heated at 95°-100° for 3 hours at which point all of theparaformaldehyde had dissolved. The infrared spectrum at this pointshowed no NH₂ bands at 3200, 3380 or 1612-1618 cm⁻¹ but instead, had NHbands at 1522-1530 and a large OH at 3280-3360 cm⁻¹. This product,applied in water solution, along with 1% ammonium chloride, to cottoncloth at 20% dry add-on and cured at 130°-150° C. for 5 min., affords adurable flame retardant finish.

EXAMPLE 21 Copolycondensation Product Modified by N-Methylolacrylamide

A mixture of 500 g. of the crude copolycondensation product of Example9, plus 50.5 g. of anhydrous N-methylolacrylamide and 0.5 g. ofp-methoxyphenol (as inhibitor) was stirred and heated at 88°-91° for 2hours while bubbling air through the mixture to further inhibitpolymerization. The product was centrifuged to remove some solidpolymeric by-product. The supernatant syrup was water-soluble.

When applied (in aqueous solution) to cotton cloth at 20% dry add-onalong with 1% potassium persulfate and polymerized thereon by exposureto superheated steam, a durable flame-retardant finish is obtained.

EXAMPLE 22 Copolycondensation Product Modified by Pentaerythritol.

A mixture of 760 g. of the crude copolycondensation product of Example 9plus 49 g. of pentaerythritol (1 mole for 2 molar equivalents of cyclicester as determined by alcohol KOH and aqueous NaOH titrations) washeated at 95°-105° for 3 hours. At this point, the alcoholic KOHtitration and aqueous NaOH titration were found to be approximatelyequivalent (0.2 meq/g.). The reaction mixture was then treated withethylene oxide for 41/2 hours at 90°-100° until it was acid-free. Theproduct was a water soluble syrup of 26,000 cps. viscosity at 25°.

It is an effective flame retardant at 5-15 phr in a rigid urethane foam.

EXAMPLE 23 Copolycondensation Product of the Invention in aMelamineformaldehyde Resin-impregnated Paper

An admixture of 0.75 parts of the 2.14:1dimethylmethylphosphonate/tris(2-chloroethyl) phosphatecopolycondensation product of Example 9 with 2 parts ofmelamineformaldehyde resin was dissolved at 12% total concentration inethanol applied to paper of the type used in automotive air filters. Theimpregnated paper was then dried and cured at 177° C. for 10 minutes.Essentially no smoke or visible vapors were emitted during the curingprocess. The resultant paper containing the cured resin and flameretardant was found to be self-extinguishing when ignited from thebottom in a vertical position. To achieve the same level of flameretardancy a higher level was required of the homopolycondensationproduct of tris(2-chloroethyl) phosphate, and a significant amount ofvisible vapor and ethylene dichloride was evolved from the latterLikewise, a higher level was required and considerable visible vapor wasevolved under these cure conditions using a commercially availableoligomeric 2-chloroethyl phosphonate (Phosgard C22R, a product of theMonsanto Company) as flame retardant.

When the alcohol treatment step used in the preparation of thecopolycondensation product is omitted, excessively fast and variablecure times are the result when the product is used as described above.

EXAMPLE 24 Allylation of a Copolycondensation Product of a Phosphonateand Phosphate, and Subsequent Bromination

To 100 parts by weight of crude 2.14:1 copolycondensation product ofdimethyl methylphosphonate and tris(2-chloroethyl) phosphate (preparedas in Example 9) at 150°-167° was slowly added (over 8 hours) 10 partsby weight of allyl chloride, this amount being calculated as equimolarto the CH₃ --O--P groups in the copolycondensate. The evolved methylchloride was separated continuously by means of a fractionating columnwhich caused 30% of the added allyl chloride to be retained and to bereacted. The resultant viscous liquid product in the reactor was foundby infrared and n.m.r. spectroscopy to have practically all of theoriginal CH₃ --O--P groups replaced by CH₂ ═CHCH₂ O--P groups.

This product when dissolved in water and applied at 20% dry add-on ontocotton cloth along with N-methylolacrylamide at 10% dry add-on plus 0.5%potassium persulfate catalyst, and then dried and cured at 100°-150° C.,afforded a durable flame retardant finish.

This product can also be additively brominated to afford a water-solublebromine-phosphorus finishing reagent for the flame-retarding ofcotton-polyester fabric. The allylated product was treated with 17 wt.%of elemental bromine, and allowed to stand at ambient temperature untilreaction was completed. After sparging and subjecting the product to themethanol and ethylene oxide steps as described in preceding examples, aneutral water-soluble gray syrup was obtained. Addition of 1% by weightof 70% hydrogen peroxide reduced the color.

As illustrated by the examples above, the products of the invention havebroad utility and high efficiency as flame retardants for plasticelastomers, coatings, adhesives, and textiles. In general any physicallyappropriate mode of incorporation of these products as additives may beemployed. In the case of plastics they may be admixed in the melt, addedto a solution, or blended with the solid plastic before casting,extrusion, molding, calendaring, coating, impregnating, vulcanizing, orother processing. Generally, effective amounts will be found within therange of 2% to 50%, depending on the nature of the substrate and thedegree of flame retardancy required as will be readily understood bythose skilled in the art of flame retardancy.

Many variations of the process and products of the invention arepossible. For example, one can include, in addition to the phosphate andphosphonate reactants, an aliphatic dihalide having both halogen atomslocated on primary carbon atoms, Suitable aliphatic dihalides includecompounds of the structure X-alkylene-X, X--CH₂ CH═CHCH₂ X, and X--CH₂CH₂ --(OCH₂ CH₂)_(n) X (n=0 to 4) and X--CH₂ CH₂ --O--CH₂ --OCH₂ CH₂ Xwhere the alkylene group is of 2 to 10 carbon atoms; suitable speciesare BrCH₂ CH₂ Br, ClCH₂ Cl, ClCH₂ CH═CHCH₂ Cl, and ClCH₂ CH₂ OCH₂ OCH₂CH₂ Cl. The aliphatic dihalide may be substituted for part of the (XCH₂CH₂ O)₃ P═O reactant. Where X--CH₂ CH═CHCH₂ X is used, the final productmay be additively brominated to enhance the flame retardant effect. Afurther variant on the process and products of the invention is theinclusion, amongst the reactants, of a primary aliphatic halide, alkenylhalide, (i.e., vinyl methyl halide), or benzyl halide. By use of asaturated primary alkyl halide, such as n- or isobutyl chloride chainends are produced and by this means, the molecular weight of the productmay be deliberately limited for example, in order to obtain a lessviscous product. By use of a higher alkyl halide, such as laurylchloride, the products acquire a surfactant character due to theirpossession of a lipid group on a hydrophilic polymer chain. By use of anunsaturated alkenyl halide such as allyl chloride, or vinylbenzylchloride, polymerizability and copolymerizability may be imparted to theproduct permitting its use as a cross-linkable monomer in, for example,polyester resins, or sites for additions of bromine may be supplied. Byuse of a benzyl halide such as benzyl chloride better solubility in, forexample, styrene or methyl methacrylate, or polymers thereof, may beimparted.

What is claimed is:
 1. A copolycondensation product of a tris(β-haloalkyl) phosphate and a dialkyl phosphonate consisting essentially of a polymer having repeating units of the structure ##STR27## in which Q is alkylene of from 2 to 4 carbon atoms, R is alkyl of from 1 to 4 carbon atoms and R' is alkyl of from 1 to 20 carbon atoms, alkenyl of from 3 to 20 carbon atoms, or phenyl optionally substituted with alkyl of from 1 to 4 carbon atoms, said polycondensation product obtained by the steps of (1) heating in the presence of a nucleophilic catalyst a tris(β-haloalkyl) phosphate of the formula

    (XQO).sub.3 P=O

in which X is halogen and Q is as defined herein, with a dialkyl phosphonate of the formula ##STR28## in the ratio of about 2 moles of dialkyl phosphonate per mole of tris(β-haloalkyl) phosphate, to obtain a crude polycondensation product having acidic structures, and (2) substantially neutralizing said acidic structures by heating the crude product with an epoxide or an orthoester.
 2. A copolycondensation product according to claim 1 in which the neutralization step takes place at a temperature of from about 50° to 150° C. with an epoxide.
 3. A copolycondensation product according to claim 2 in which the epoxide is ethylene oxide.
 4. A copolycondensation product according to claim 1 in which Q is ethylene, X is chlorine, and R and R' are methyl.
 5. The copolycondensation product according to claim 4 in which ethylene oxide is employed in the neutralization step.
 6. A copolycondensation product of a tris(β-haloalkyl) phosphate having from 2 to 4 carbon atoms in each alkyl moiety and a dialkyl phosphonate of the formula ##STR29## in which R' is alkyl of from 1 to 20 carbon atoms, alkenyl of from 3 to 20 carbon atoms, or phenyl optionally substituted with alkyl of from 1 to 4 carbon atoms and/or halogen, and R is alkyl of from 1 to 4 carbon atoms, said product being obtained by the steps of (1) heating the phosphate with at least 2 moles of the dialkyl phosphonate per mole of phosphate in the presence of a nucleophilic catalyst to obtain a crude polycondensation product having acidic structures, and (2) substantially neutralizing said acidic structures by heating the crude product with an epoxide or an orthoester.
 7. A copolycondensation product according to claim 6 in which the neutralization step takes place at a temperature of from about 50° to about 150° C. with an epoxide.
 8. A copolycondensation product according to claim 7 in which the epoxide is ethylene oxide.
 9. A copolycondensation product of tris(2-chloroethyl) phosphate and dimethyl methylphosphonte obtained by the steps of (1) heating tris(2-chloroethyl) phosphate with dimethyl methylphosphonate, in a molar ratio of at least 2 moles of methylphosphonate per mole of phosphate, in the presence of a nucleophilic catalyst to obtain a crude polycondensation having acidic structures and (2) substantially neutralizing said acidic structures by heating the crude product with an epoxide or an orthoester.
 10. The copolycondensation product according to claim 9 in which ethylene oxide is employed in the neutralization step. 